allow relocation of srmclient scripts

many of the srm scripts point to the generic srm script in
/usr/sbin/srm without using considering $SRM_PATH. This causes
problems if the scripts are installed in different locations than the
ones defined in the RPM.

This patch changes the default location of the generic srm script from
/usr/sbin/srm to ${SRM_PATH}/sbin which is /usr/share/srm/sbin by
default and changes all other scripts to use "${SRM_PATH}/sbin/srm",
thus allowing relocation of the scripts.

Ticket: http://rt.dcache.org/Ticket/Display.html?id=7989
Acked-by:
Target: trunk
Require-book: no
Require-notes: yes